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%I #11 Apr 27 2020 23:58:03
%S 0,0,0,0,1,1,1,2,2,2,2,1,0,0,0,0,1,1,1,2,2,2,3,3,3,3,3,4,4,4,4,4,5,5,
%T 5,6,6,6,6,5,4,4,4,3,3,3,2,1,0,0,0,0,1,1,1,2,2,2,2,1,0,0,0,0,1,1,1,2,
%U 2,2,3,3,3,3,3,4,4,4,4,4,5,5,5,6,6,6,7
%N a(n) is the X-coordinate of the point at n steps backward from the origine along the space filling curve U defined in A334188; sequence A334223 gives Y-coordinates.
%H Rémy Sigrist, <a href="/A334222/b334222.txt">Table of n, a(n) for n = 0..8318</a>
%H Rémy Sigrist, <a href="/A334222/a334222.gp.txt">PARI program for A334222</a>
%H <a href="/index/Con#coordinates_2D_curves">Index entries for sequences related to coordinates of 2D curves</a>
%F A334188(A334223(n), a(n)) = -n.
%e The "backward" branch of curve U starting from the origin is as follows:
%e | |
%e 7| -15..-16 -21..-22 -31..-32 -37
%e | | | | | | | |
%e 6| -14 -17 -20 -23 -30 -33 -36
%e | | | | | | | |
%e 5| -13 -18..-19 -24 -29 -34..-35
%e | | | |
%e 4| -12..-11..-10 -25 -28
%e | | | |
%e 3| -3...-4 -9 -26..-27
%e | | | |
%e 2| -2 -5 -8
%e | | | |
%e 1| -1 -6...-7
%e | |
%e 0| 0
%e ---+-----------------------------------
%e y/x| 0 1 2 3 4 5 6
%e - hence a(4) = a(5) = a(6) = a(11) = a(16) = a(17) = a(18) = 1.
%o (PARI) See Links section.
%Y Cf. A334188, A334223.
%K nonn
%O 0,8
%A _Rémy Sigrist_, Apr 19 2020